Electric fuse with a plurality of fusible elements arranged in spaced groups radially



Oct. 20, 1964 T F. BRANDT, JR

ELECTRIC FUSE WITH A PLURALITY OF FUSIBLE ELEMENTS ARRANGED IN RADIAL-LY SPACED GROUPS 2 Sheets-Sheet 2 Filed Sept. 13 1962 lNVENTOR THOMAS E BRA v0T,JR., 5) W WM 9.

ATTORNEY.

United States Patent 3,153,713 ELECTRIC FUllll Wli'lfl A PLURAMTY 0F FUSEELE ELEMENTS ARRANGED EN SPA'CED GllflllllS RADllAlLlLY Thomas F. Elsi-melt, lira, Swarthmore, Pa, assignor to General Electric @ompany, a corporation of New York Filed Sept. 13, 1962, Ser. No. assu es 2 Claims. (QB. Edd-132) The present invention relates to an electric fuse and more particularly to an electric fuse of the cartridge type having an improved arrangement for positioning fusible elements therein.

An electric fuse of the cartridge type utilizes a cylindrical fuse body to enclose one or more fusible links or elements. The fusible elements are conventiona ly sus pended within the fuse body between a pair of support members located at opposite ends thereof. Several methods are known for securing the elements to the support members in the desired arrangement. The respective ends of each element are sometimes soldered or spot Welded to the support members. In another methot' which is more economical and easier to assemble, extensions of the fusible elements are clamped between the support member edge or an outer wall of the fuse body and a suitable terminal cap fitted over each end of the fuse body. This clamping arrangement provides a sound physical structure while ensuring electrical continuity between each element and the respective caps. However, in such a prior art cartridge fuse having any given number of elements arranged in parallel in the fuse body, the fuse caliber has had to be undesirably large in order that the support member have an adequately long perimeter where the fusible elements are attached.

Accordingly, it is a primary object of my invention to provide a new and improved electric fuse of the cartridge type which is relatively inexpensive to manufacture, easy to assemble and which accommodates in a relatively small diameter body an unusually large number of fusible elements.

Another object of the present invention is to provide a new and improved electric fuse having a support arrangement for multiple groups of fusible elements.

Yet another object of the invention is to provide an electric fuse having a novel support arrangement which facilitates assembly and enables a predetermined number of elements to be suspended in parallel spaced relationship within a relatively small amount of space.

Briefly, in accordance with the invention, I provide a new and improved electric fuse of the cartridge type having a hollow, tube-like casing in which a plurality of spacedapart, fusible metal elements are suspended in generally parallel relation to the longitudinal axis of the casin in order to position the elements in at least two separate groups spaced at unequal distances from the longitudinal axis of the casing, I provide means including a first pair of disc-like members disposed, respectively, across opposite ends of the casing with each member of the first pair having a relatively large central aperture through which the elements extend. Each of these embers is arranged to accommodate, along the inner perimeter which defines the central aperture therein, a first group of the elements, whereby the elements comprising this group are supported with adequate spacing from each other and from the inner wall of the casing. I further provide a second pair of disc-like members overlying, respectively, the members of the aforesaid first pair, and each member of the second pair has a relatively small central aperture through which all of the elements except those in said first group extend. Each of the sec-0nd pair of members is arranged along the inner perimeter which defines its aperture to accommodate a second group of the elements which are thus supported closer to the axis of the casing than the elements of the first group. An electroconduotive end cap is fitted over each end of the casing, and opposite ends of the fusible elements are folded over the respective disc-like members so as to be clamped between an outer surface of the casing wall and the associated end cap.

The organization and operation together with further objects and advantages of the invention may best be understood by reference to the following description taken in connection with the accompanying drawings, in which:

PEG. 1 is an elevation partly broken away of an electric fuse arrangement of the invention;

FIG. 2 is an enlarged fragmentary sectional view of the electric fuse arrangement of FIG. 1;

FIG. 3 is a plan view of a support member for the electric fuse arrangement of FIG. 1;

PEG. 4 is a plan view of another support member for the electric fuse arrangement of PEG. 1;

PEG. 5 is an enlarged sectional View of the fuse along lines -5 of FIG. 1;

PK}. 6 is a fragmentary plan view of a modification of each of the support members shown in FIGS. 3 and 4;

FIG. 7 is an enlarged sectional View of a support member of PEG. 6 along the line 7--7; and

FIG. 8 is an enlarged fragmentary sectional View of the electric fuse arrangement of FIG. 1 utilizing the support members shown by FIG. 6.

Referring to FIGS. 1 and 2, the electric fuse arrangement of the invention has an insulating casing or body comprising an enclosing wall l0 which is open at opposite ends thereof. The casing it. is tube-like in appearance, and while preferably annular in cross-section it may have a polygonal or any otl er desi ed geometrical cross-section. The enclosing wall defines a cavity or opening 11 extending through the casing id as shown by FIGS. 1 and 2.

A first support means in the form of an apertured disc member 2.3, more clearly shown by FIG. 3, has a diameter approximately equal to the outside diameter of the casing Till. A pair of tiese members are disposed across and axially engage opposite ends of the casing, respectively. The disc members 13 accommodate respective ones of a plurality of fusible metal elements, such as the ribbon elements 14, in associated ones of a series of notches 15 formed in the inner perimeter 16 of each member 13. The illustrated elements 14- comprise an outer ring or group of fusible elements which are positioned by the members 13 in parallel with and at a predetermined distance from the centerline or longitudinal axis 10a. of the casing iii. Each fusible element 14 is bent or folded to extend radially over the surface 13 of the supporting disc member 13 and then again bent so that its end is disposed against the outer surface 24 of the casing wall Till. The disc member 13 shown by FIG. 3 supports ten fusible elements in predetermined spaced relation to each other and to an inner surface 21 of the casing ill.

in accordance with my invention, second support means in the form of another pair of apertured disc members 23 is provided. Each of the members 23, as can be seen in HQ. 4, has a central aperture 24 which is smaller than the central aperture 17 in member 13 (FIG. 3). The members 23 overlie, respectively, the associated members 13 and accommodate, in notches 25 located along the inner perimeter 26 which defines the aperture 2 5 in each member 23, a plurality of additional fusible metal elements, such as the ribbon elements 28. While the ele nents 2.8 pass through both apertures 17 and 24, as is best seen in FIG. 2, the elements 14 extend only through aperture 17 and their radially oriented portions are sandwiched between the surface 13 of the disc member 13 and a surface 29 of the disc member 23. Each disc member 23 has an outside diameter that is equal to or less than the diameter of the casing 19, as shown by FlGS. l and 2 in a preferred embodiment of the invention.

The illustrated elements 28 comprise an inner ring or group of fusible elements which are positioned by the disc member 13 in spaced-apart parallel relationship with respect to the axis 16211 of the casing 19, with each element 28 being located closer to the axis than any of the elements 14. Thus the inner and outer groups of fusible elements are supported in spaced radial relationship, and as a result the respective elements are quite evenly distributed throughout the available space inside the casing ill. Although the inner group as shown comprises four elements 2% equidistantly spaced from the axis ltla, it should be apparent that other quantities and varied spacings might be used in practicing my invention.

Each fusible element 23 is folded over surface 3% of the supporting disc member 23, and in a fashion similar to that of the fuse elements 14, it is also bent so that its end is disposed against the outer surface Ztl of the casing lt Small alignment holes 31 and 32- are provided in the respective members 13 and 23 for proper line up of these members during assembly, and the notches l and are so disposed that the elements 14 in the outer group are angularly misaligned with respect to the elements 28 in the inner group. This is best seen in FIG. 5, and it is apparent that the respective element ends do not overlap one another where they adjoin the casing surface A closure means in the form of an electroconductive, cup-like end cap 35 encloses each end of the casing it Each end cap 35 is fitted over the disc members 13 and 23 and onto the casing end, thereby holding the disc members in place. The end cap 35 has a dimension such that it is forced onto the casing lit to clamp the folded ends of fuse elements 14 and 28 between the outer surface 20 of the casing lit and an inner surface 36 of the end cap, and in this manner good electrical contact is made between each fusible element and the cap 35. If desired, a crimping operation may be added to insure securing the element ends.

Thus, it can be seen that the plurality of fusible elements, such as elements 14 and 23, are positioned in separate concentrically located radially spaced groups consisting of the outer group comprising elements 14 supported by disc member 13 and the inner group comprising elements 28 supported by disc member 23. The spacings between the axis 1% of the casing in and the respective groups of fusible elements are determined by the dimensions of the apertures 17 and 24- in the respective support means or annular disc members 13 and 23. In the embodiment of the invention shown by FIGS. 1 and 2, the fusible elements 14 and 2%; are in strip or ribbon form having rectangular crosssections. As Will be apparent from the drawings, particularly FIG. 5, the widest transverse dimension of each fusible ribbon element extends generally tangentially of the fuse casing iii. However, in accordance with the invention, fusible elements of other cross-sectional shapes or configurations can be positioned by disc members suitably adapted to accommodate the particular elements used. In any event, satisfactory support is provided for a given number of properly spaced parallel elements in a fuse body of smaller size than has heretofore been possible.

FIG. 6 shows a modification of the disc member of the invention as previously discussed and shown by FIGS. 3 and 4. The outer periphery 37 of each disc member 13 and 23 has, in the form shown by FIG. 6, three spaced-apart tabs (13a, 13:), 13c and 23a, 23b, 23c) developed by radial cuts in the respective disc members l3 and 23. Only tabs 13a, 23b and 23c are visible J in FIG. 6. Each tab is bent away from the plane of the respective disc members as shown by FIG. 7. In FIG. 8, tab 13c in disc 13 receives tab 23c of disc 23 and facilitates the positioning and securing of the respective disc members 13 and 23 to the tubular casing iii.

If it is desired, the opening illl shown by FIGS. 1, 2 and 8 can be filled with an arc-quenching substance. The arc-quenching 1 ler performs a well-known function and is introduced dependent upon the requirements of the specific fuse use.

As will be evidenced from the foregoing description, certain aspects of the invention are not limited to the particular details of the constructions illustrated. It is contemplated that additional disc members or the like may be utilized to provide support for at least one other group of fusible elements concentrically positioned within the fuse casing in spaced relationship to the elements 14 and 23. Other modifications and applications will no doubt occur to those skilled in the art. Therefore, it is intended that the appended claims shall cover such modifications and applications that do not depart from the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In an electric fuse:

(a) a tube-like casing having openings at opposite ends thereof;

(b) a plurality of spaced-apart, fusible metal elements of ribbon form suspended inside said casing in generally parallel relation to its longitudinal axis, each of said ribbon-form elements being arranged with its largest transverse dimension extending in a generally tangential direction with respect to said casing;

(0) means for positioning said elements in a plurality of separate groups spaced unequally from said longitudinal axis, said positioning means including (i) a first pair of disc-like members disposed across said openings, respectively, each member of said first pair having a relatively large central aperture through which said elements extend and being arranged to accommodate, along its perimeter defining said aperture, the elements comprising one of said groups, and

(ii) a second pair of disc-like members overlying, respectively, the members of said first pair with each member of said second pair having a central aperture which is smaller than the central aperture in either member of said first pair and through which all of the elements except those comprising said one group extend, each member of said second pair being arranged to accommodate along its perimeter defining the aperture therein, the elements comprising another of said groups; and

(d) two cup-like electroconductive end caps one on each end of said casing, with opposite ends of said elements being folded over the respective members of said first and second pairs and being clamped between outer surfaces of said casing and said end caps, respectively;

(e) and means for locating the fusible elements of said first group in angularly misaligned relationship with respect to the fusible elements of said second group and in such positions that the element ends which are clamped between said casing and each of said end caps are out of angularly overlapping relationship with one another.

2. An electric cartridge fuse comprising:

(a) an insulating casing having an axial opening therethrough;

(b) a plurality of fusible elements of ribbon form within said casing, each of said ribbon-form elements being arranged with its largest transverse dimension extending in a generally tangential direction with respect to said casing;

, 5 6 (c) a pair of electroconductive end caps; (g) and means for locating the fusible elements of said (d) a first pair of disc members respectively engaging first group in angularly misaligned relationship with opposite ends of said casing and including means respect to the fusible elements of said second group for supporting therebetween a predetermined group and in such positions that the element ends which of said elements; and 5 are clamped between said casing and each of said (2) a second pair of disc members overlying, respecend caps are out of angularly overlapping relationtively, the disc members of said first pair and includship With one another. ing means for supporting therebetween another group of said elements in spaced radial relationship with References Cited in the file of this Patent said predetermined group; 10 UNITED STATES PATENTS (f) said end caps being fitted over said disc members P and onto said opposite ends of the casing With oppo- 2866O37 Stewart 1958 site ends of said elements being clamped between FOREIGN PATENTS the casing and the end caps, respectively; 167,397 Australia Apr. 6, 1956 

1. IN AN ELECTRIC FUSE: (A) A TUBE-LIKE CASING HAVING OPENINGS AT OPPOSITE ENDS THEREOF; (B) A PLURALITY OF SPACED-APART, FUSIBLE METAL ELEMENTS OF RIBBON FORM SUSPENDED INSIE SAID CASING IN GENERALLY PARALLEL RELATION TO ITS IONGITUDINAL AXIS, EACH OF SAID RIBBON-FORM ELEMENTS BEING ARRANGED WITH ITS LARGEST TRANSVERSE DIMENSION EXTENDING IN A GENERALLY TANGENTIAL DIRECTION WITH RESPECT TO SAID CASING: (C) MEANS FOR POSITIONING SAID ELEMENTS IN A PLURALITY OF SEPARATE GROUPS SPACED UNEQUALLY FROM SAID LONGITUDINAL AXIS, SAID POSITIONING MEANS INCLUDING (I) A FIRST PAIR OF DISC-LIKE MEMBERS DISPOSED ACROSS SAID OPENINGS, RESPECTIVELY, EACH MEMBER OF SAID FIRST PAIR HAVING A RELATIVELY LARGE CENTRAL APERTURE THROUGH WHICH SAID ELEMENTS EXTEND AND BEING ARRANGED TO ACCOMMODATE, ALONG ITS PERIMETER DEFINING SAID APERTURE, THE ELEMENTS COMPRISING ONE OF SAID GROUPS, AND (II) A SECOND PAIR OF DISC-LIKE MEMBERS OVERLYING, RESPECTIVELY, THE MEMBERS OF SAID FIRST PAIR WITH EACH MEMBER OF SAID SECOND PAIR HAVING A CENTRAL APERATURE WHICH IS SMALLER THAN THE CENTRAL APERTURE IN EITHER MEMBER OF SAID FIRST PAIR AND THROUGH WHICH ALL OF THE ELEMENTS EXCEPT THOSE COMPRISING SAID ONE GROUP EXTEND, EACH MEMBER OF SAID SECOND PAIR BEING ARRANGED TO ACCOMMODATE ALONG ITS PERIMETER DEFINING THE APERTURE THEREIN, THE ELEMENTS COMPRISING ANOTHER OF SAID GROUPS; AND (D) TWO CUP-LIKE ELECTROCONDUCTIVE END CAP ONE OF EACH END OF SAID CASING, WITH OPPOSITE ENDS OF SAID ELEMENTS BEING FOLDED OVER THE RESPECTIVE MEMBERS OF SAID FIRST AND SECOND PAIRS AND BEING CLAMPED BETWEEN OUTER SURFACES OF SAID CASING AND SAID END CAPS, RESPECTIVELY; (E) AND MEANS FOR LOCATING THE FUSIBLE ELEMENTS OF SAID FIRST GROUP IN ANGULARLY MISALIGNED RELATIONSHIP WITH RSPECT TO THE FUSIBLE ELEMENTS OF SAID SECOND GROUP AND IN SUCH POSITIONS THAT THE ELEMENT ENDS WHICH ARE CLAMPED BETWEEN SAID CASING AND EACH OF SAID END CAPS ARE OUT OF ANGULARLY OVERLAPPING RELATIONSHIP WITH ONE ANOTHER. 